-LRB- CNN -RRB- The former imperial capital of Hue sits just below what was once the demilitarized zone between North and South Vietnam and was , near the end of the war , the site of some of its fiercest fighting . You 've seen it in newsreel footage -- and recreated -LRB- in England -RRB- in Stanley Kubrick 's `` Full Metal Jacket . ''

It 's one of the few areas of Vietnam I 've never been .

Hue is , in many ways , a city of ghosts , of memories and spirits -- and we play on that in Sunday 's episode .

It begins with a camera movement inside a `` Spirit House '' -- the dollhouse-sized shrines that many believers keep outside their homes and businesses . The Vietnamese are largely ancestor worshippers . Helping your deceased relatives into the next life -- and making sure they are happy while there -- is important .

On special days and holidays , families visit temples and pagodas and leave offerings , often food , sometimes replicas of money or appliances or luxuries for the departed . Things they liked in life that might make the afterlife more comfortable .

Spirit houses , as I understand them , are designed to deal with the problem of hungry , dissatisfied spirits who may not be settled , who have , for one reason or another , unfinished business left behind . They sit out front , or near the house or store , usually filled with incense and offerings , in the hope of distracting the spirits away from the main destination .

In the weeks following the initial North Vietnamese taking of the city of Hue , many hundreds -- if not thousands -- of citizens , deemed dangerous or counterrevolutionary or otherwise undesirable , were summarily executed and buried in unmarked mass graves by the communist forces .

When the United States Marines and army of South Vietnam retook the city , it was only at the end of brutal , house-to-house fighting and finally , airstrikes , that Hue was retaken -- flattening much of the city in the process . Many , many people were lost , their bodies never identified or recovered . This , the inability to find the physical remains of a relative , is a particular agony to Vietnamese .

For this reason , this episode is haunted by ghosts . We had n't intended it to be so . But that definitely emerged as a theme .

You feel it as you drive the streets and early morning rice paddies on a scooter , walk the parapets of the ancient citadel , look at the flag hanging in the mist across the Perfume River .

At one point , a young woman I 'm having dinner with casually mentions that her mother does n't like her to go out after dark . Too many ghosts .

I do n't want you to think that this episode of `` Parts Unknown '' is some kind of a bummer -- a depressing discussion of a war about which there are still strong feelings and disagreements here . It 's not .

One of the crazily awesome , incongruous things about Vietnam that I 've found from the first time I visited is how friendly , welcoming , quick to move beyond the past the Vietnamese are .

It is an incredibly beautiful country . One filled with passionate , proud cooks , and opinionated , enthusiastic eaters . You will see me with some old friends -- and you will , as always in Vietnam , see me eating some amazing food .

And if you thought pho was the best thing ever ?

Wait 'til you see Bun Bo Hue .

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Anthony Bourdain returns to a country he 's loved since his first visit

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The city of Hue , Vietnam , is a city of spirits and ghosts

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The episode deals with the past , but also with the vibrant present